Use of solubilizers for homogenizing additive concentrates

ABSTRACT

A cold-stabilized fuel oil composition comprising a major proportion by weight of a middle distillate fuel which boils in the range of 120-500° C. and minor proportions by weight of
         (A) at least one cold flow improver,   (B) at least one detergent additive and   (C) at least one cold solubilizer I       

     
       
         
         
             
             
         
       
         
         
           
             which has at least one radical having at least 4 carbon atoms.

The present invention relates to the use of specific dicarboxylic acidderivatives as solubilizers for homogenizing additive concentrates whichcomprise cold flow improvers, detergent additives, inert organicsolvents and if appropriate cetane number improvers. The inventionfurther relates to additive concentrates suitable for additizing fueloil compositions which consist predominantly of a middle distillate fuelwhich boils in the range of 120-500° C. and/or a renewable fuel, saidadditive concentrates having the ingredients mentioned.

In the formulation or storage of additive concentrates which, as well ascold flow improvers which are typically added to the diesel fuels andheating oils in the mineral oil refineries, also comprise detergentadditives and cetane number improvers which form the main constituentsof so-called diesel performance packages, there are frequentoccurrences - especially at temperatures significantly below 20° C.—offlaky precipitates which cannot be filtered off; attempted filtrationcan lead to filter conglutination. At least, such additive concentratesare, however, generally slightly to highly turbid. The presence ofadditionally used organic solvents in the additive concentrates cannotprevent such flaky precipitates or turbidities. The flaky precipitates,which usually at first remain more or less dispersed in the solution,can subsequently lead to severe sedimentation or to gel formation in theadditive concentrate.

It was therefore an object of the present invention to stabilize suchadditive concentrates which comprise both cold flow improvers anddetergent additives, and also inert organic solvents and if appropriatecetane number improvers, such that the flaky precipitates or turbiditiesdescribed do not occur in the course of formulation and storage of theadditive concentrates.

Accordingly, the use has been found of at least one solubilizer of thegeneral formula I

in which

-   -   R¹ denotes a hydrocarbylene radical having from 1 to 12 carbon        atoms or a hydrocarbylene radical which has from 2 to 12 carbon        atoms, is interrupted by one or more heteroatoms selected from        the group of O, S and N, and may in each case bear one or more        functional groups selected from the group of OH, OR³, NH₂, NHR⁴,        NR⁴R⁵, COOH, COOR⁷, CONHR⁴ and CONR⁴R⁵, where amino groups may        also be present in protonated form and carboxylic acid groups        also in deprotonated form,    -   X is OH, OR³, NH₂, NHR⁴ or NR⁴R⁵, where, in the case that X        together with the adjacent carbonyl group is a carboxylic acid        radical, this radical is present in deprotonated form and the        accompanying cation may be a hydrocarbyl-substituted ammonium        cation selected from the group of [H₃NR⁸]⁺, [H₂NR⁸R⁹]⁺ and        [HNR⁸R⁹R¹⁰]⁺,    -   Y is O, S, NH or NR⁶, or, in the case that X is NH₂ or NHR⁴, is        a chemical bond to X with formation of an imide structure,        where R² to R¹⁰ are each independently hydrocarbyl radicals        having from 1 to 30 carbon atoms,

with the proviso that at least one of the R², R³, R⁴, R⁵, R⁶ and R⁷radicals has at least 4 carbon atoms,

for homogenizing additive concentrates suitable for additizing fuel oilcompositions which consist predominantly of a middle distillate fuelwhich boils in the range of 120-500° C. and/or a renewable fuel, saidadditive concentrates comprising

-   (A) at least one cold flow improver,-   (B) at least one detergent additive and-   (C) an inert organic solvent or a mixture of such solvents.

The additive concentrates mentioned preferably additionally comprise

-   (D) at least one cetane number improver.

However, the action of the solubilizers I used according to theinvention also occurs in principle in additive concentrates which do notcomprise any cetane number improver.

In a preferred embodiment, the solubilizers I used in accordance withthe invention are used to homogenize additive concentrates whichcomprise

-   -   (A) from 1 to 50% by weight, especially from 2 to 40% by weight,        in particular from 3 to 20% by weight, of at least one cold flow        improver,    -   (B) from 0.5 to 40% by weight, preferably from 0.7 to 20% by        weight, especially from 1 to 12% by weight, in particular from        1.5 to 7% by weight, of at least one detergent additive,    -   (C) from 1 to 60% by weight, especially from 3 to 50% by weight,        in particular from 5 to 40% by weight, of an inert organic        solvent or of a mixture of such solvents and    -   (D) from 0 to 80% by weight, especially from 25 to 75% by        weight, in particular from 40 to 70% by weight, of at least one        cetane number improver.

The additive concentrates mentioned may additionally comprise furtheringredients, in which case the sum of all ingredients adds up to 100% byweight.

In the context of the present invention, homogenization shall beunderstood to mean the prevention or the elimination of the flakyprecipitates or turbidities described above in the additiveconcentrates.

The specific dicarboxylic acid derivatives of the general formula I usedas solubilizers in the present invention are known from WO 2007/131894.They are recommended there as cold stabilization enhancers in fuel oilcompositions which comprise customary cold flow improvers and detergentadditives, in low dosages—specifically from 1 to 2000 ppm by weight,based on the fuel oil composition. Corresponding additive concentratesor technical problems to be solved with such additive concentrates arenot addressed in WO 2007/131894.

EP-A 807 676 discloses low-sulfur middle distillate fuels which, toimprove their lubricity, comprise carboxamides, for example also amidesof C₃- to C₄₀-dicarboxylic acids, cold flow improvers and ashlessdispersants. The additives mentioned may also be added to the middledistillate fuels in the form of a concentrate which typically alsocomprises diluents or solvents.

Compounds of the type of the general formula I mentioned are also knownas gasoline fuel additives. For instance, EP-A 301 448 describes alkalimetal or alkaline earth metal salts of amides of di-, tri- ortetracarboxylic acids, for example monoamides of dicarboxylic acids suchas maleic acid, as valve seat wear-reducing additives for gasolinefuels. Similarly, EP-A 555 006 discloses the wear-reducing action ofdicarboxylic acid derivatives such as the reaction product of maleicanhydride with a secondary amine to give the monoamide in the form ofthe alkali metal salt in internal combustion engines operated withgasoline fuel.

EP-A 798 364 describes amides obtained by condensation reactions ofcarboxylic acids with aliphatic amines as additives for diesel fuels forreducing deposits at the injection nozzles, for increasing the lubricityof the fuel and for reducing the wear of the injection pumps. Theseamides are based preferably on relatively long-chain mono-carboxylicacids, especially having from 8 to 30 carbon atoms, such as oleic acid,and on relatively long-chain amines, especially those having from 8 to20 carbon atoms, such as oleylamine or oleylpropylenediamine. However,dodecenylsuccinic acid and its anhydride are also mentioned as astarting material for such amides. The amides mentioned may be usedtogether with other customary diesel additives such as low-temperatureflow improvers, cetane number improvers, antioxidants, metaldeactivators, rust and corrosion inhibitors, demulsifiers and foaminhibitors.

The compounds of the general formula I are dicarboxylic acidderivatives. Depending on the definition of the variables X and Y, theyare present especially in the form of monoesters, monothioesters,monoamides, diesters, bisthioesters, diamides or mixed derivativeshaving in each case two different functions from the group of the ester,thioester and amide functions or are joined to form a cycle via an imidefunction.

The variable R¹ in the compounds I is the bridging member between thetwo carbonyl carbon atoms. A hydrocarbylene radical shall be understoodhere to mean a divalent hydrocarbon radical of any structure which,however, in accordance with the definition, may also compriseheteroatoms and/or functional groups. The hydrocarbenyl radical may besaturated, unsaturated or of aromatic nature; it may have a linear,branched or cyclic structure.

R¹ preferably denotes a linear or branched alkylene group having from 1to 12, especially from 2 to 8, in particular from 2 to 6 carbon atoms,for example methylene, 1,1-ethylene, 1,2-ethylene, 1,3-propylene,1,2-propylene, 1,2-butylene, 1,2-hexylene, 1,2-octylene, 1,2-decylene,1,2-dodecylene, tetramethylene, pentamethylene or hexamethylene, a1,2-vinylidene group of the formula —CH═CH—, a 1,2-, 1,3- or1,4-phenylene group, or a heteroarylene group, for example based on thepyridine skeleton.

Compounds of the formula I which comprise benzene or pyridine skeletonsfor R¹ are based, for example, on benzenedi-, -tri- or -tetracarboxylicacids such as phthalic acid (benzene-1,2-dicarboxylic acid), isophthalicacid (benzene-1,3-dicarboxylic acid), terephthalic acid(benzene-1,4-dicarboxylic acid), trimellitic acid(benzene-1,2,4-tri-carboxylic acid), trimesic acid(benzene-1,3,5-tricarboxylic acid) or pyromellitic acid(benzene-1,2,4,5-tetracarboxylic acid) or on pyridinedicarboxylic acidssuch as quinolinic acid (pyridine-2,3-dicarboxylic acid), lutidinic acid(pyridine-2,4-dicarboxylic acid), dipicolinic acid(pyridine-2,6-dicarboxylic acid) or dinicotinic acid(pyridine-3,5-dicarboxylic acid). In the case of pyromellitic acidhaving 4 carboxyl groups, a doubling of the dicarboxylic acid structureI can occur, such that the active structure of the solubilizer of thegeneral formula I occurs twice in the molecule.

Hydrocarbylene radicals interrupted by heteroatoms from the group of O,S and N for R¹ are especially C₁- to C₁₂-alkylene groups which comprise,incorporated in their chain, one, two or three oxygen, sulfur and/ornitrogen atoms, where, in the case of nitrogen atoms, their free valenceis preferably saturated by a lower alkyl group such as methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl;examples thereof are —CH₂—O—CH₂—, —CH₂CH₂—O—CH₂—CH₂—, —CH₂—N(CH₃)—CH₂—,—CH₂CH₂—N(CH₃)—CH₂—CH₂ and —CH₂CH₂—O—CH₂CH₂—O—CH₂CH₂—.

When amino groups are present in protonated form or carboxylic acidgroups in deprotonated form in the compounds of the general form 1, theaccompanying counterions are such that the compounds I still havesufficient oil solubility. In the case of protonated amino groups, it ispossible, for example, for carboxylates of long-chain fatty acids orlong-chain alkanesulfonates to occur as anions; for this purpose,preference is given to using those having at least one C₈- to C₂₀-alkylor -alkenyl radical. In the case of deprotonated carboxylic acids,preferably hydrocarbyl-substituted ammonium cations selected from thegroup of [H₃NR⁸]⁺, [H₂NR⁸R⁹]⁺ and [HNR⁸R⁹R¹⁰]⁺ occur as cations; thevariables R⁸, R⁹ and R¹⁰ therein each independently denote preferablylinear or branched alkyl radicals such as methyl, ethyl, vinyl,n-propyl, isopropyl, 1-propenyl, 2-propenyl, n-butyl, sec-butyl,isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl,2-ethylhexyl, neooctyl, nonyl, neononyl, decyl, 2-propylheptyl,neodecyl, undecyl, neoundecyl, dodecyl, tridecyl, isotridecyl,tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl (stearyl),oleyl, linolyl, linolenyl, nonadecyl, eicosyl, hencosyl, docosyl,tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl,nonacosyl, squalyl or the constitution isomers thereof.

When the R², R³, R⁴, R⁵, R⁶ or R⁷ radicals are a hydrocarbyl radicalhaving from 1 to 30 carbon atoms, it shall be understood here to mean avirtually purely hydrocarbon radical of any structure, which, however,provided that this does not distort the dominant hydrocarbon character,may still have, to a small degree, heteroatoms, for example O or N,and/or functional groups with heteroatoms, for example OH groups. Thishydrocarbyl radical may be of saturated, unsaturated or aromatic nature;it may have a linear, branched or cyclic structure.

In the context of the present invention, such a hydrocarbyl radicalhaving from 1 to 30 carbon atoms for one of the R², R³, R⁴, R⁵, R⁶ or R⁷radicals is preferably a linear or branched alkyl or alkenyl radicalsuch as methyl, ethyl, vinyl, n-propyl, isopropyl, 1-propenyl,2-propenyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl,hexyl, heptyl, octyl, 2-ethylhexyl, neooctyl, nonyl, neononyl, decyl,2-propylheptyl, neodecyl, undecyl, neoundecyl, dodecyl, tridecyl,isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl(stearyl), oleyl, linolyl, linolenyl, nonadecyl, eicosyl, hencosyl,docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl,octacosyl, nonacosyl, squalyl or their constitutional isomers. Suchrelatively long-chain alkyl radicals may also stem from naturallyoccurring sources, especially from glycerides or the parent fatty acids.

In the context of the present invention, such a hydrocarbyl radicalhaving from 1 to 30 carbon atoms for one of the R², R³, R⁴, R⁵, R⁶ or R⁷radicals may also be an aryl, alkaryl or arylalkyl radical, for examplephenyl, naphthyl, benzyl, 2-phenylethyl, 3-phenylpropyl, 4-phenylbutyl,or o-, m- or p-xylyl.

At least one of the R², R³, R⁴, R⁵, R⁶ or R⁷ radicals in thesolubilizers I must have at least 4, preferably at least 6, especiallyat least 8, more preferably at least 10, in particular at least 12carbon atoms, in order that the compounds I have the necessary oilsolubility. Such relatively long-chain radicals are typically present inthe form of linear or slightly branched alkyl or alkenyl chains asdescribed above. The remaining R², R³, R⁴, R⁵, R⁶ or R⁷ radicals arethen typically short-chain, i.e. they have generally from 1 to 4 carbonatoms, or the corresponding valences in the compound I are saturated byhydrogen.

In a preferred embodiment, at least one solubilizer I in which at leastone of the R², R³, R⁴, R⁵, R⁶ or R⁷ radicals has at least 4, preferablyat least 6, especially at least 8, more preferably at least 10, inparticular at least 12 carbon atoms, is used for the present inventionto homogenize additive concentrates.

In a further preferred embodiment, at least one solubilizer I in whichthe variable X is OH is used for the present invention; they are thenespecially dicarboxylic monoesters, dicarboxylic monothioesters ordicarboxylic monoamides.

In a further preferred embodiment, at least one solubilizer I whichderives from maleic acid or phthalic acid, i.e. the bridging member R¹is a 1,2-vinylidene group of the formula —CH═CH— or a 1,2-phenylenegroup, is used for the present invention.

More preferably, the solubilizer I used in accordance with the inventionis a monoamide of maleic acid or of phthalic acid (Y═NR⁶), in which atleast one of the R² and R⁶ radicals has at least 10 and especially atleast 12 carbon atoms. Such maleic and phthalic monoamides satisfy theformula HOOC—R¹—CO—NR²R⁶ (R¹=1,2-vinylidene or 1,2-phenylene) in whichone of the R² and R⁶ radicals or both R² and R⁶ radicals are ahydrocarbyl radical having from 10 to 30 and from 12 to 30 carbon atomsrespectively. One example thereof is the monoamide of maleic acid orphthalic acid and tridecylamine (R²=tridecyl, R⁶=H), which is obtainablein a known manner by reacting maleic acid or maleic anhydride, orphthalic acid or phthalic anhydride, with tridecylamine in an equimolarratio. Preference is given here to using a tridecylamine which ispresent in the form of a mixture of structural isomers ofn-tridecylamine and branched tridecylamines, where the proportion ofn-tridecylamine is generally less than 70 mol%, especially less than 50mol %, in particular less than 35 mol %.

The solubilizers I used in accordance with the invention are present inthe additive concentrates generally in an amount of from 1.05 to 15% byweight, preferably from 1.25 to 13.5% by weight, more preferably from1.5 to 12% by weight, especially from 2.0 to 10% by weight, inparticular from 2.5 to 7% by weight, based in each case on the totalamount of the additive concentrate. In most cases, the preferred rangesmention-ed are sufficient to obtain a sufficient homogenizing action inthe additive concentrates. However, it is also possible to use more than15% by weight of solubilizers 1, for example up to 20 or up to 30% byweight, but no further significant enhancement of the desired effect isthus achieved. In contrast to the upper limit, the lower limit for theamount of solubilizers I used in accordance with the invention iscritical; it has been found that amounts up to 1% by weight arefrequently still not sufficient to obtain the desired homogenization.

In the context of the present invention, cold flow improvers ofcomponent (A) shall be understood to mean all additives which improvethe cold properties of fuel oil compositions. In addition to the actualcold flow improvers (“MDFIs”, for example ethylenevinyl acetatecopolymers), these are in particular also nucleators, paraffindispersants (“WASAs”, for example certain polar nitrogen compounds) orthe combination of MDFIs and WASAs (“WAFIs”) (cf. also Ullmann'sEncyclopedia of Industrial Chemistry, 5th edition, Volume A16, p. 719ff.).

Such cold flow improvers for the present invention as component

-   -   (A) should advantageously be one or more representatives        selected from    -   (Aa) copolymers of ethylene with at least one further        ethylenically unsaturated monomer;    -   (Ab) comb polymers;    -   (Ac) polyoxyalkylenes;    -   (Ad) polar nitrogen compounds;    -   (Ae) sulfocarboxylic acids or sulfonic acids or derivatives        thereof; and/or (Af) poly(meth)acrylic esters.

In the copolymers of ethylene with at least one further ethylenicallyunsaturated monomer of group (Aa), the monomer is preferably selectedfrom alkenylcarboxylic esters, (meth)acrylic esters and olefins.

Suitable olefins are, for example, those having from 3 to 10 carbonatoms and having from 1 to 3, preferably having 1 or 2 carbon-carbondouble bonds, in particular having one carbon-carbon double bond. In thelatter case, the carbon-carbon double bond may be arranged eitherterminally (α-olefins) or internally. However, preference is given toα-olefins, particular preference to α-olefins having from 3 to 8 carbonatoms, such as propene, 1-butene, 1-pentene, 1-hexene and 1-octene.

Suitable (meth)acrylic esters are, for example, esters of (meth)acrylicacid with C₁-C₁₄-alkanols, especially with methanol, ethanol, propanol,isopropanol, n-butanol, sec-butanol, isobutanol, tert-butanol, pentanol,hexanol, heptanol, octanol, 2-ethylhexanol, nonanol, decanol,2-propylheptanol, dodecanol and tetradecanol.

Suitable alkenylcarboxylic esters are, for example, the vinyl andpropenyl esters of carboxylic acids having from 2 to 20 carbon atomswhose hydrocarbon radical may be linear or branched. Among these,preference is given to the vinyl esters. Among the carboxylic acidshaving a branched hydrocarbon radical, preference is given to thosewhose branch is disposed in the α-position to the carboxyl group, andparticular preference is given to the α-carbon atom being tertiary, i.e.the carboxylic acid is a neocarboxylic acid. However, preference isgiven to the hydrocarbon radical of the carboxylic acid being linear.

Examples of suitable alkenylcarboxylic esters are vinyl acetate, vinylpropionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl neopentanoate,vinyl hexanoate, vinyl neononanoate, vinyl neodecanoate and thecorresponding propenyl esters, preference being given to the vinylesters. A particularly preferred alkenylcarboxylic ester is vinylacetate; typical copolymers of group (Aa) resulting therefrom areethylene-vinyl acetate copolymers (“EVA”), which are used in dieselfuels on a large scale.

Particular preference is given to the ethylenically unsaturated monomerbeing selected from alkenylcarboxylic esters.

Also suitable are copolymers which comprise two or more differentcopolymerized alkenylcarboxylic esters which differ in the alkenylfunction and/or in the carboxylic acid group. Likewise suitable arecopolymers which, in addition to the alkenylcarboxylic ester(s),comprise at least one copolymerized olefin and/or at least onecopolymerized (meth)acrylic ester.

The ethylenically unsaturated monomer is copolymerized in the copolymerof group (Aa) in an amount of preferably from 1 to 50 mol %, morepreferably from 10 to 50 mol % and in particular from 5 to 20 mol %,based on the overall copolymer.

The copolymer of group (Aa) preferably has a number-average molecularweight Mn of from 500 to 20 000, more preferably from 7500 to 10 000 andin particular from 1000 to 6000.

Comb polymers of group (Ab) are, for example, those described in“Comb-Like Polymers. Structure and Properties”, N. A. Plate and V. P.Shibaev, J. Poly. Sci. Macromolecular Revs. 8, pages 117 to 253 (1974).Among those described there, suitable comb polymers are, for example,those of the formula II

where

-   D is R¹⁷, COOR¹⁷, OCOR¹⁷, R¹⁸, OCOR¹⁷ or OR¹⁷,-   E is H, CH₃, D or R¹⁸,-   G is H or D,-   J is H, R¹⁸, R¹⁸COOR¹⁷, aryl or heterocyclyl,-   K is H, COOR¹⁸, OCOR¹⁸, OR¹⁸ or COOH,-   L is H, R¹⁸, COOR¹⁸, OCOR¹⁸, COOH or aryl,    where-   R¹⁷ is a hydrocarbon radical having at least 10 carbon atoms,    preferably having from 10 to 30 carbon atoms,-   R¹⁸ is a hydrocarbon radical having at least one carbon atom,    preferably having from 1 to 30 carbon atoms,-   m is a molar fraction in the range from 1.0 to 0.4 and-   n is a molar fraction in the range from 0 to 0.6.

Preferred comb polymers are, for example, obtainable by copolymerizationof maleic anhydride or fumaric acid with another ethylenicallyunsaturated monomer, for example with an α-olefin or an unsaturatedester, such as vinyl acetate, and subsequent esterification of theanhydride or acid function with an alcohol having at least 10 carbonatoms. Further preferred comb polymers are copolymers of α-olefins andesterified comonomers, for example esterified copolymers of styrene andmaleic anhydride or esterified copolymers of styrene and fumaric acid.Also suitable are mixtures of comb polymers. Comb polymers may also bepolyfumarates or polymaleates. Homo- and copolymers of vinyl ethers arealso suitable comb polymers.

Suitable polyoxyalkylenes of group (Ac) are, for example,polyoxyalkylene esters, ethers, ester/ethers and mixtures thereof. Thepolyoxyalkylene compounds preferably comprise at least one linear alkylgroup, more preferably at least two linear alkyl groups, having from 10to 30 carbon atoms and a polyoxyalkylene group having a molecular weightof up to 5000. The alkyl group of the polyoxyalkylene radical preferablycomprises from 1 to 4 carbon atoms. Such polyoxyalkylene compounds aredescribed, for example, in EP-A-0 061 895 and also in U.S. Pat. No.4,491,455, which are hereby fully incorporated by reference. Preferredpolyoxyalkylene esters, ethers and ester/ethers have the general formulaIll

R¹⁹[O—(CH₂)_(y)]_(x)O—R²⁰   (III)

in which

-   R¹⁹ and R²⁰ are each independently R²¹, R²¹—CO—, R²¹—O—CO(CH₂)₂— or    R²¹—O—CO(CH₂)₂—-   CO— where R²¹ is linear C₁-C₃₀-alkyl,-   y is from 1 to 4,-   x is from 2 to 200, and-   z is from 1 to 4.

Preferred polyoxyalkylene compounds of the formula III in which both R¹⁹and R²⁰ are R²¹ are polyethylene glycols and polypropylene glycolshaving a number-average molecular weight of from 100 to 5000. Preferredpolyoxyalkylenes of the formula III in which one of the R¹⁹ radicals isR²¹ and the other is R²¹—CO— are polyoxyalkylene esters of fatty acidshaving from 10 to 30 carbon atoms, such as stearic acid or behenic acid.Preferred polyoxyalkylene compounds in which both R¹⁹ and R²⁰ are anR²¹—CO— radical are diesters of fatty acids having from 10 to 30 carbonatoms, preferably of stearic acid or behenic acid.

The polar nitrogen compounds of group (Ad), which are advantageouslyoil-soluble, may be either ionic or nonionic and preferably have atleast one substituent, more preferably at least 2 substituents, of theformula >NR²² in which R²² is a C₈-C₄₀-hydrocarbon radical. The nitrogensubstituents may also be quaternized, i.e. be in cationic form. Anexample of such nitrogen compounds is that of ammonium salts and/oramides which are obtainable by the reaction of at least one aminesubstituted by at least one hydrocarbon radical with a carboxylic acidhaving from 1 to 4 carboxyl groups or with a suitable derivativethereof. The amines preferably comprise at least one linear C₈-C₄₀-alkylradical. Suitable primary amines are, for example, octylamine,nonylamine, decylamine, undecylamine, dodecylamine, tetradecylamine andthe higher linear homologs. Suitable secondary amines are, for example,dioctadecylamine and methylbehenylamine. Also suitable are aminemixtures, in particular amine mixtures obtainable on the industrialscale, such as fatty amines or hydrogenated tallamines, as described,for example, in Ullmann's Encyclopedia of Industrial Chemistry, 6thEdition, “Amines, aliphatic” chapter. Acids suitable for the reactionare, for example, cyclo-hexane-1,2-dicarboxylic acid,cyclohexene-1,2-dicarboxylic acid, cyclopentane-1,2-di-carboxylic acid,naphthalenedicarboxylic acid, phthalic acid, isophthalic acid,terephthalic acid and succinic acids substituted with long-chainhydrocarbon radicals.

A further example of polar nitrogen compounds of group (Ad) is that ofring systems which bear at least two substituents of the formula-A-NR²³R²⁴ in which A is a linear or branched aliphatic hydrocarbongroup which is optionally interrupted by one or more groups selectedfrom O, S, NR³⁵ and CO, and R²³ and R²⁴ are each a C₉-C₄₀-hydrocarbonradical which is optionally interrupted by one or more groups selectedfrom O, S, NR³⁵ and CO, and/or substituted by one or more substituentsselected from OH, SH and NR³⁵R³⁶ where R³⁵ is C₁-C₄₀-alkyl which isoptionally interrupted by one or more moieties selected from CO, NR³⁵, Oand S, and/or substituted by one or more radicals selected from NR³⁷R³⁸,OR³⁷, SR³⁷, COR³⁷, COOR³⁷, CONR³⁷R³⁸, aryl or heterocyclyl, where R³⁷and R³⁸ are each independently selected from H or C₁-C₄-alkyl; and R³⁶is H or R³⁵.

A is preferably a methylene or polymethylene group having from 2 to 20methylene units. Examples of suitable R²³ and R²⁴ radicals are2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-ketopropyl,ethoxyethyl and propoxypropyl. The cyclic system may be homocyclic,heterocyclic, fused polycyclic or nonfused polycyclic systems. The ringsystem is preferably carbo- or heteroaromatic, in particularcarboaromatic. Examples of such polycyclic ring systems are fusedbenzoid structures such as naphthalene, anthraxcene, phenanthrene andpyrene, fused nonbenzoid structures such as azulene, indene, hydrindeneand fluorene, nonfused polycycles such as diphenyl, heterocycles such asquinoline, indole, dihydroindole, benzofuran, coumarin, isocoumarin,benzothiophene, carbazole, diphenylene oxide and diphenylene sulfide,nonaromatic or partially saturated ring systems such as decalin, andthree-dimensional structures such as α-pinene, camphene, bornylene,norbornane, norbornene, bicyclooctane and bicyclooctene.

A further example of suitable polar nitrogen compounds is that ofcondensates of long-chain primary or secondary amines with carboxylgroup-containing polymers.

The polar nitrogen compounds mentioned here are described in WO 00/44857and also in the references cited therein, which are hereby fullyincorporated by reference.

Suitable polar nitrogen compounds are also described, for example, inDE-A-198 48 621, DE-A-196 22 052 or EP-B 398 101, which are herebyincorporated by reference.

Suitable sulfo carboxylic acids/sulfonic acids or their derivatives ofgroup (Ae) are, for example, those of the general formula IV

in which

-   Y′ is SO₃ ⁻(NR²⁵ ₃R²⁶)⁺, SO₃ ⁻(NHR²⁵ ₂R²⁶)⁺, SO₃ ⁻(NH₂R²⁵R²⁶), SO₃    ⁻(NH₃R²⁶) or-   SO₂NR²⁵R²⁶,-   X′ is Y′, CONR²⁵R²⁷, CO₂ ⁻(NR²⁵ ₃R²⁷)⁺, CO₂ ⁻(NHR²⁵ ₂R²⁷)⁺,    R²⁸—COOR²⁷, NR²⁵COR²⁷, R²⁸OR²⁷, R²⁸OCOR²⁷, R²⁸R²⁷, N(COR²⁵)R²⁷ or    Z-(NR²⁵ ₃R²⁷)⁺,-   where-   R²⁵ is a hydrocarbon radical,-   R²⁶ and R²⁷ are each alkyl, alkoxyalkyl or polyalkoxyalkyl having at    least 10 carbon atoms in the main chain,-   R²⁸ is C₂-C₅-alkylene,-   Z— is one anion equivalent and-   A′ and B are each alkyl, alkenyl or two substituted hydrocarbon    radicals or, together with the carbon atoms to which they are    bonded, form an aromatic or cycloaliphatic ring system.

Such sulfo carboxylic acids and sulfonic acids and their derivatives aredescribed in EP-A-0 261 957, which is hereby fully incorporated byreference.

Suitable poly(meth)acrylic esters of group (Af) are either homo- orcopolymers of acrylic and methacrylic esters. Preference is given tocopolymers of at least two different (meth)acrylic esters which differin the esterified alcohol. Optionally, the copolymer comprises anotherdifferent copolymerized olefinically unsaturated monomer. Theweight-average molecular weight of the polymer is preferably from 50 000to 500 000. A particularly preferred polymer is a copolymer ofmethacrylic acid and methacrylic esters of saturated C₁₄- andC₁₅-alcohols, in which the acid groups have been neutralized withhydrogenated tallamine. Suitable poly(meth)acrylic esters are described,for example, in WO 00/44857, which is hereby fully incorporated byreference.

The additive concentrates mentioned preferably comprise, as component(A), at least one cold flow improver of group (Aa) or a mixture of oneor more cold flow improvers of group (Aa) and one or more cold flowimprovers selected from the remaining groups (Ab) to (Af), especially amixture of one or more cold flow improvers of group (Aa) and one or morecold flow improvers of group (Ad).

More preferably, the additive concentrates mentioned comprise, as coldflow improvers of components (A), one or more representatives selectedfrom

-   -   ethylene-vinyl acetate copolymers [representatives of group        (Aa)];    -   ethylene-vinyl propionate copolymers [representatives of group        (Aa)];    -   N,N-dialkylammonium salts of 2-N′,N′-dialkylamidobenzoates        [representatives of group (Ad)], for example the reaction        product formed from 1 mol of phthalic anhydride and 2 mol of        ditallow fatty amine, the latter being hydrogenated or        unhydrogenated;    -   the reaction products of 1 mol of ethylenediaminetetraacetic        acid with 4 mol of a dialkylamine [representatives of group        (Ad)], for example the reaction product formed from 1 mol of        ethylenediaminetetraacetic acid and 4 mol of ditallow fatty        amine, the latter being hydrogenated or unhydrogenated;    -   the reaction products of 1 mol of nitrilotriacetic acid with 3        mol of a dialkylamine [representatives of group (Ad)], for        example the reaction product formed from 1 mol of        nitrilotriacetic acid and 3 mol of ditallow fatty amine, the        latter being hydrogenated or unhydrogenated;    -   the reaction products of 1 mol of phthalic anhydride with 2 mol        of a dialkylamine [representatives of group (Ad)], for example        the reaction product formed from 1 mol of phthalic anhydride and        2 mol of ditallow fatty amine, the latter being hydrogenated or        unhydrogenated;    -   the reaction products of 1 mol of an alkenyl-spiro-bislactone        with 2 mol of a dialkylamine [representatives of group (Ad)],        for example the reaction product formed from 1 mol of an        alkenyl-spiro-bislactone with 2 mol of ditallow fatty amine        and/or tallow fatty amine, the latter two being hydrogenated or        unhydrogenated;    -   C₁₂- to C₁₈-alkyl fumarate-vinyl acetate or C₁₂- to C₁₈-alkyl        fumarate-styrene comb polymers [representatives of group (Ab)],        for example those in the molar ratio of the two monomer types of        1:1; and/or    -   C₁₄- to C₂₀-alkyl itaconate comb polymers [representatives of        group (Ab)].

The detergent additives of component (B) to be used in the additiveconcentrates mentioned are generally advantageously amphiphilicsubstances which have at least one hydrophobic hydrocarbon radicalhaving a number-average molecular weight (Mn) of from 85 to 20 000 andat least one polar moiety which is selected from

-   -   (Ba) mono- or polyamino groups having up to 6 nitrogen atoms, at        least one nitrogen atom having basic properties;    -   (Bb) nitro groups, if appropriate in combination with hydroxyl        groups;    -   (Bc) hydroxyl groups in combination with mono- or polyamino        groups, at least one nitrogen atom having basic properties;    -   (Bd) carboxyl groups or their alkali metal or alkaline earth        metal salts;    -   (Be) sulfonic acid groups or their alkali metal or alkaline        earth metal salts;    -   (Bf) polyoxy-C₂-C₄-alkylene moieties which are terminated by        hydroxyl groups, mono- or polyamino groups, at least one        nitrogen atom having basic properties, or by carbamate groups;    -   (Bg) carboxylic ester groups;    -   (Bh) moieties which derive from succinic anhydride and have        hydroxyl and/or amino and/or amido and/or imido groups; and/or    -   (Bi) moieties obtained by Mannich reaction of substituted        phenols with aldehydes and mono- or polyamines.

The hydrophobic hydrocarbon radical in the above detergent additives,which ensures the adequate solubility in the fuel oil composition, has anumber-average molecular weight (Mn) of from 85 to 20 000, especiallyfrom 113 to 10 000, in particular from 300 to 5000. Typical hydrophobichydrocarbon radicals, especially in conjunction with the polar moieties(Ba), (Bc), (Bh) and (Bi), include relatively long-chain alkyl oralkenyl groups, especially the polypropenyl, polybutenyl andpolyisobutenyl radical, each having Mn=from 300 to 5000, especially from500 to 2500, in particular from 700 to 2300.

Examples of the above groups of detergent additives include thefollowing:

Additives comprising mono- or polyamino groups (Ba) are preferablypolyalkenemono- or polyalkenepolyamines based on polypropene orconventional (i.e. having predominantly internal double bonds)polybutene or polyisobutene having Mn=from 300 to 5000. When polybuteneor polyisobutene having predominantly internal double bonds (usually inthe beta- and gamma-position) are used as starting materials in thepreparation of the additives, a possible preparative route is bychlorination and subsequent amination or by oxidation of the double bondwith air or ozone to give the carbonyl or carboxyl compound andsubsequent amination under reductive (hydrogenating) conditions. Theamines used here for the amination may be, for example, ammonia,monoamines or polyamines, such as dimethylaminopropylamine,ethylenediamine, diethylenetriamine, triethylenetetramine ortetraethylenepentamine. Corresponding additives based on polypropene aredescribed in particular in WO-A-94/24231.

Further preferred additives comprising monoamino groups (Ba) are thehydrogenation products of the reaction products of polyisobutenes havingan average degree of polymerization P of from 5 to 100 with nitrogenoxides or mixtures of nitrogen oxides and oxygen, as described inparticular in WO-A-97/03946.

Further preferred additives comprising monoamino groups (Ba) are thecompounds obtainable from polyisobutene epoxides by reaction with aminesand subsequent dehydration and reduction of the amino alcohols, asdescribed in particular in DE-A-196 20 262.

Additives comprising nitro groups (Bb), if appropriate in combinationwith hydroxyl groups, are preferably reaction products of polyisobuteneshaving an average degree of polymerization P=from 5 to 100 or from 10 to100 with nitrogen oxides or mixtures of nitrogen oxides and oxygen, asdescribed in particular in WO-A-96/03367 and WO-A-96/03479. Thesereaction products are generally mixtures of pure nitropoly-isobutenes(e.g. α,β-dinitropolyisobutene) and mixed hydroxynitropolyiso-butenes(e.g. α-nitro-β-hydroxypolyisobutene).

Additives comprising hydroxyl groups in combination with mono- orpolyamino groups (Bc) are in particular reaction products ofpolyisobutene epoxides obtainable from polyisobutene having preferablypredominantly terminal double bonds and Mn=from 300 to 5000, withammonia or mono- or polyamines, as described in particular in EP-A 476485.

Additives comprising carboxyl groups or their alkali metal or alkalineearth metal salts (Bd) are preferably copolymers of C₂-C₄₀-olefins withmaleic anhydride which have a total molar mass of from 500 to 20 000 andof whose carboxyl groups some or all have been converted to the alkalimetal or alkaline earth metal salts and any remainder of the carboxylgroups has been reacted with alcohols or amines. Such additives aredisclosed in particular by EP-A-307 815. Such additives serve mainly toprevent valve seat wear and can, as described in WO-A-87/01126,advantageously be used in combination with customary fuel detergentssuch as poly(iso)buteneamines or polyetheramines.

Additives comprising sulfonic acid groups or their alkali metal oralkaline earth metal salts (Be) are preferably alkali metal or alkalineearth metal salts of an alkyl sulfosuccinate, as described in particularin EP-A-639 632. Such additives serve mainly to prevent valve seat wearand can be used advantageously in combination with customary fueldetergents such as poly(iso)buteneamines or polyetheramines.

Additives comprising polyoxy-C₂-C₄-alkylene moieties (Bf) are preferablypolyethers or polyether amines which are obtainable by reaction ofC₂-C₆₀-alkanols, C₆-C₃₀-alkane-diols, mono- or di-C₂-C₃₀-alkylamines,C₁-C₃₀-alkylcyclohexanols or C₁-C₃₀-alkylphenols with from 1 to 30 molof ethylene oxide and/or propylene oxide and/or butylene oxide perhydroxyl group or amino group and, in the case of the polyether amines,by subsequent reductive amination with ammonia, monoamines orpolyamines. Such products are described in particular in EP-A-310 875,EP-A-356 725, EP-A-700 985 and U.S. Pat. No. 4,877,416. In the case ofpolyethers, such products also have carrier oil properties. Typicalexamples of these are tridecanol butoxylates, isotridecanol butoxylates,isononylphenol butoxylates and polyisobutenol butoxylates andpropoxylates and also the corresponding reaction products with ammonia.

Additives comprising carboxylic ester groups (Bg) are preferably estersof mono-, di- or tricarboxylic acids with long-chain alkanols orpolyols, in particular those having a minimum viscosity of 2 mm²/s at100° C., as described in particular in DE-A-38 38 918. The mono-, di- ortricarboxylic acids used may be aliphatic or aromatic acids, andparticularly suitable ester alcohols or ester polyols are long-chainrepresentatives having, for example, from 6 to 24 carbon atoms. Typicalrepresentatives of the esters are adipates, phthalates, isophthalates,terephthalates and trimellitates of isooctanol, of isononanol, ofisodecanol and of isotridecanol. Such products also have carrier oilproperties.

Additives comprising moieties derived from succinic anhydride and havinghydroxyl and/or amino and/or amido and/or imido groups (Bh) arepreferably corresponding derivatives of alkyl- or alkenyl-substitutedsuccinic anhydride and especially the corresponding derivatives ofpolyisobutenylsuccinic anhydride which are obtainable by reactingconventional or highly reactive polyisobutene having Mn=from 300 to 5000with maleic anhydride by a thermal route or via the chlorinatedpolyisobutene. Particular interest attaches to derivatives withaliphatic polyamines such as ethylenediamine, diethylenetriamine,triethylenetetramine or tetraethylenepentamine. The moieties havinghydroxyl and/or amino and/or amido and/or imido groups are, for example,carboxylic acid groups, acid amides of monoamines, acid amides of di- orpolyamines which, in addition to the amide function, also have freeamine groups, succinic acid derivatives having an acid and an amidefunction, carboximides with monoamines, carboximides with di- orpolyamines which, in addition to the imide function, also have freeamine groups, or diimides which are formed by the reaction of di- orpolyamines with two succinic acid derivatives. Such fuel additives aredescribed in particular in U.S. Pat. No. 4,849,572.

Additives comprising moieties (Bi) obtained by Mannich reaction ofsubstituted phenols with aldehydes and mono- or polyamines arepreferably reaction products of polyisobutene-substituted phenols withformaldehyde and mono- or polyamines such as ethylenediamine,diethylenetriamine, triethylenetetramine, tetraethylenepentamine ordimethylaminopropylamine. The polyisobutenyl-substituted phenols maystem from conventional or highly reactive polyisobutene having Mn=from300 to 5000. Such “polyisobutene-Mannich bases” are described inparticular in EP-A-831 141.

For a more precise definition of the fuel additives detailedindividually, reference is explicitly made here to the disclosures ofthe abovementioned prior art documents. Particular preference is givento detergent additives from group (Bh). These are preferably thereaction products of alkyl- or alkenyl-substituted succinic anhydrides,especially of polyisobutenylsuccinic anhydrides, with amines. It will beappreciated that these reaction products are not obtainable only whensubstituted succinic anhydride is used, but also when substitutedsuccinic acid or suitable acid derivatives, such as succinyl halides orsuccinic esters, are used.

In a particularly preferred embodiment, the additive concentratesmentioned comprise, as a detergent additive of component (B), one ormore derivatives which have been derived from polyisobutenylsuccinicanhydride and have amino and/or amido and/or imido groups. Particularlypreferred detergent additives in this context arepolyisobutenyl-substituted succinimides, especially the imides withaliphatic polyamines. Particularly preferred polyamines arediethylenetriamine, tetraethylenepentamine and pentaethylenehexamine,particular preference being given to tetraethylenepentamine. Thepolyisobutenyl radical has a number-average molecular weight Mn ofpreferably from 500 to 5000, more preferably from 500 to 2000 and inparticular of about 1000.

In a further preferred embodiment, the detergent additives mentioned areused in combination with at least one carrier oil in the additiveconcentrates mentioned. Suitable mineral carrier oils are the fractionsobtained in crude oil processing, such as brightstock or base oilshaving viscosities, for example, from the SN 500-2000 class; but alsoaromatic hydrocarbons, paraffinic hydrocarbons and alkoxyalkanols.Likewise useful is a fraction which is obtained in the refining ofmineral oil and is known as “hydrocrack oil” (vacuum distillate cuthaving a boiling range of from about 360 to 500° C., obtainable fromnatural mineral oil which has been catalytically hydrogenated under highpressure and isomerized and also deparaffinized). Likewise suitable aremixtures of abovementioned mineral carrier oils.

Examples of suitable synthetic carrier oils are selected from:polyolefins (poly-alpha-olefins or poly(internal olefin)s),(poly)esters, (poly)alkoxylates, polyethers, aliphatic polyether amines,alkylphenol-started polyethers, alkylphenol-started polyether amines andcarboxylic esters of long-chain alkanols.

Examples of suitable polyolefins are olefin polymers having Mn=from 400to 1800, in particular based on polybutene or polyisobutene(hydrogenated or unhydrogenated).

Examples of suitable polyethers or polyetheramines are preferablycompounds comprising polyoxy-C₂-C₄-alkylene moieties which areobtainable by reacting C₂-C₆₀-alkanols, C₆-C₃₀-alkanediols, mono- ordi-C₂-C₃₀-alkylamines, C₁-C₃₀-alkylcyclohexanols or C₁-C₃₀-alkylphenolswith from 1 to 30 mol of ethylene oxide and/or propylene oxide and/orbutylene oxide per hydroxyl group or amino group, and, in the case ofthe polyether amines, by subsequent reductive amination with ammonia,monoamines or polyamines. Such products are described in particular inEP-A-310 875, EP-A-356 725, EP-A-700 985 and U.S. Pat. No. 4,877,416.For example, the polyether amines used may be poly-C₂-C₆-alkylene oxideamines or functional derivatives thereof. Typical examples thereof aretridecanol butoxylates or isotridecanol butoxylates, isononylphenolbutoxylates and also polyisobutenol butoxylates and propoxylates, andalso the corresponding reaction products with ammonia.

Examples of carboxylic esters of long-chain alkanols are in particularesters of mono-, di- or tricarboxylic acids with long-chain alkanols orpolyols, as described in particular in DE-A-38 38 918. The mono-, di- ortricarboxylic acids used may be aliphatic or aromatic acids; suitableester alcohols or polyols are in particular long-chain representativeshaving, for example, from 6 to 24 carbon atoms. Typical representativesof the esters are adipates, phthalates, isophthalates, terephthalatesand trimellitates of isooctanol, isononanol, isodecanol andisotridecanol, for example di-(n- or isotridecyl) phthalate.

Further suitable carrier oil systems are described, for example, inDE-A-38 26 608, DE-A-41 42 241, DE-A-43 09 074, EP-A-0 452 328 andEP-A-0 548 617, which are explicitly incorporated herein by way ofreference.

Examples of particularly suitable synthetic carrier oils arealcohol-started polyethers having from about 5 to 35, for example fromabout 5 to 30, C₃-C₆-alkylene oxide units, for example selected frompropylene oxide, n-butylene oxide and isobutylene oxide units, ormixtures thereof. Nonlimiting examples of suitable starter alcohols arelong-chain alkanols or phenols substituted by long-chain alkyl in whichthe long-chain alkyl radical is in particular a straight-chain orbranched C₆-C₁₈-alkyl radical. Preferred examples include tridecanol andnonylphenol.

Further suitable synthetic carrier oils are alkoxylated alkylphenols, asdescribed in DE-A-10 102 913.6.

Preferred carrier oils are synthetic carrier oils, particular preferencebeing given to polyethers.

When a carrier oil is also incorporated into the additive concentrate,it is added typically in an amount of from 10% by weight to 100% byweight, preferably from 20 to 70% by weight, based in each case on theamount of detergent additive of component (B).

The inert organic solvents or solvent mixtures of component (C) used inthe additive concentrates mentioned are generally those which areselected from hydrocarbons, alcohols, carboxylic esters or mixturesthereof. “Inert” means here that such organic solvents exert nosignificant interactions, if any, with the active components in theadditive concentrates or enter into chemical reactions with them underuse conditions. Such inert organic solvents or solvent mixtures areessentially free of further organic compounds with functional groups.Typical hydrocarbon solvents suitable as component (C) are n-pentane,n-hexane, n-heptane, cyclohexane, methylcyclohexane, toluene, xylenes,technical hydrocarbon mixtures such as Solvent Naphtha, as arecommercially obtainable, for example, under the name Solvesso® 150, andfuels themselves. Typical alcohols suitable as component (C) aremethanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol,2-ethylhexanol and 2-propylheptanol. Carboxylic esters suitable ascomponent (C) are, for example, fatty acid lower alkyl esters,especially fatty acid methyl esters.

The cetane number improvers of component (D) are also referred to asignition or combustion improvers. The component (D) to be used in theadditive concentrates mentioned is preferably at least one cetane numberimprover which is selected from organic nitrates. Such organic nitratesare especially nitrate esters of unsubstituted or substituted, aliphaticor cycloaliphatic alcohols, usually having up to about 10 and inparticular having from 2 to 10 carbon atoms. The alkyl group in thesenitrate esters may be linear or branched, saturated or unsaturated.Typical examples of such nitrate esters are methyl nitrate, ethylnitrate, n-propyl nitrate, isopropyl nitrate, allyl nitrate, n-butylnitrate, isobutyl nitrate, sec-butyl nitrate, tert-butyl nitrate, n-amylnitrate, isoamyl nitrate, 2-amyl nitrate, 3-amyl nitrate, tert-amylnitrate, n-hexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octylnitrate, 2-ethylhexyl nitrate, sec-octyl nitrate, n-nonyl nitrate,n-decyl nitrate, 2-propylheptyl nitrate, cyclopentyl nitrate, cyclohexylnitrate, methylcyclohexyl nitrate and isopropylcyclohexyl nitrate.Additionally suitable are, for example, nitrate esters ofalkoxy-substituted aliphatic alcohols, such as 2-ethoxyethyl nitrate,2-(2-ethoxyethoxy)ethyl nitrate, 1-methoxypropyl nitrate or4-ethoxybutyl nitrate. Also suitable are diol nitrates such as1,6-hexamethylene dinitrate. Among the cetane number improver classesmentioned, primary amyl nitrates, primary hexyl nitrates, octyl nitratesand mixtures thereof are preferred.

Particular preference is given to 2-ethylhexyl nitrate as component (D).2-Ethylhexyl nitrate may be present as the sole cetane number improveror in a mixture with other cetane number improvers.

In addition, the additive concentrates mentioned may comprise furthercustomary coadditives, especially boosters for the cold flow improvers(A), such as oleic acid-diethylenetriamine reaction products, corrosioninhibitors, deicing agents such as ethylene glycol mono- or dimethylethers, demulsifiers, dehazers, antifoams, lubricity improvers, metaldeactivators, antioxidants or stabilizers, antistats, metallocenes,markers and/or dyes. These customary coadditives are, if desired, addedin amount relative to the components (A) to (C) or (A) to (D) which arecustomary therefor.

In the context of the present invention, fuel oil compositions shall beunderstood to mean middle distillate fuels which boil within the rangeof 120-500° C., renewable fuels and mixtures thereof. Such middledistillate fuels are in particular diesel fuel, heating oil or kerosene,particular preference being given to heating oil and in particulardiesel fuel. Such renewable fuels are bioethanol and in particularbiodiesel.

The heating oils are, for example, low-sulfur or sulfur-rich crude oilraffinates or bituminous or brown coal distillates which typically havea boiling range of from 150 to 400° C. The heating oils may be standardheating oil according to DIN 51603-1, which has a sulfur content of from0.005 to 0.2% by weight, or they are low-sulfur heating oils having asulfur content of from 0 to 0.005% by weight. Examples of heating oilinclude in particular heating oil for domestic oil-fired boilers or ELheating oil. The quality requirements for such heating oils are laiddown, for example, in DIN 51603-1 (cf. also Ullmann's Encyclopedia ofIndustrial Chemistry, 5th edition, Volume A12, p. 617 ff., which ishereby explicitly incorporated by reference).

The diesel fuels are, for example, crude oil raffinates which typicallyhave a boiling range from 100 to 400° C. These are usually distillateshaving a 95% point up to 360° C. or even higher. They may also beso-called “ultra low sulfur diesel” or “city diesel”, characterized by a95% point of, for example, not more than 345° C. and a sulfur content ofnot more than 0.005% by weight, or by a 95% point of, for example, 285°C. and a sulfur content of not more than 0.001% by weight. In additionto the diesel fuels obtainable by refining crude oil, suitable dieselfuels also include those obtainable by coal gasification or gasliquefaction [“gas-to-liquid” (“GTL”) fuels] or by biomass liquefaction[“biomass-to-liquid” (“BTL”) fuels]. Also suitable are mixtures of theaforementioned diesel fuels with renewable fuels such as biodiesel orbioethanol.

The diesel fuels are more preferably those having a low sulfur content,i.e. having a sulfur content of less than 0.05% by weight, preferably ofless than 0.02% by weight, in particular of less than 0.005% by weightand especially of less than 0.001% by weight of sulfur.

Biodiesel (also referred to as biofuel oil) preferably comprisesessentially alkyl esters of fatty acids which derive from vegetableand/or animal oils and/or fats. Alkyl esters are understood to meantypically lower alkyl esters, especially C₁- to C₄-alkyl esters, whichare obtainable by transesterifiying the glycerides which occur invegetable and/or animal oils and/or fats, especially triglycerides, bymeans of lower alcohols, for example ethanol, n-propanol, isopropanol,n-butanol, isobutanol, sec-butanol, tert-butanol or especially methanol(“FAME”: fatty acid methyl esters).

The examples of vegetable oils which are converted to correspondingalkyl esters and can thus serve as the basis for biodiesel are castoroil, olive oil, peanut oil, palm kernel oil, coconut oil, mustard oil,cottonseed oil and especially sunflower oil, palm oil, soybean oil andrapeseed oil. Further examples include oils which can be obtained fromwheat, jute, sesame and the shea tree nut; it is also possible to usearachis oil, jatropha oil and linseed oil.

It is also possible to convert vegetable oils which have already beenused, for example used deep fat fryer oil, if appropriate afterappropriate cleaning, to alkyl esters and hence for them to serve as thebasis for biodiesel.

Vegetable fats are likewise usable in principle as a source forbiodiesel, but are of minor importance.

Examples of animal fats and oils which are converted to correspondingalkyl esters and can thus serve as the basis for biodiesel are fish oil,bovine tallow, porcine tallow and similar fats and oils obtained aswastes in the slaughter or utilization of farm animals or wild animals.

The parent saturated or unsaturated fatty acids of the vegetable and/oranimal oils and/or fats mentioned, said fatty acids usually having from12 to 22 carbon atoms and possibly bearing additional functional groupssuch as hydroxyl groups, which occur in the alkyl esters are especiallylauric acid, myristic acid, palmitic acid, stearic acid, oleic acid,linoleic acid, linolenic acid, elaidic acid, erucic acid and ricinoleicacid, especially in the form of mixtures of such fatty acids.

Typical lower alkyl esters based on vegetable and/or animal oils and/orfats which find use as biodiesel or biodiesel components are, forexample, sunflower methyl ester, palm oil methyl ester (“PME”), soybeanoil methyl ester (“SME”) and especially rapeseed oil methyl ester(“RME”).

However, it is also possible to use the monoglycerides, diglycerides andespecially triglycerides themselves, for example castor oil, or mixturesof such glycerides as biodiesel or components for biodiesel.

The present invention also provides additive concentrates suitable foradditizing fuel oil compositions which consist predominantly of a middledistillate fuel which boils in the range of 120-500° C. and/or arenewable fuel, said additive concentrate comprising at least onesolubilizer of the general formula I

in which

-   -   R¹ denotes a hydrocarbylene radical having from 1 to 12 carbon        atoms or a hydrocarbylene radical which has from 2 to 12 carbon        atoms, is interrupted by one or more heteroatoms selected from        the group of O, S and N, and may in each case bear one or more        functional groups selected from the group of OH, OR³, NH₂, NHR⁴,        NR⁴R⁵, COOH, COOR⁷, CONHR⁴ and CONR⁴R⁵, where amino groups may        also be present in protonated form and carboxylic acid groups        also in deprotonated form,

X is OH, OR³, NH₂, NHR⁴ or NR⁴R⁵, where, in the case that X togetherwith the adjacent carbonyl group is a carboxylic acid radical, thisradical is present in deprotonated form and the accompanying cation maybe a hydrocarbyl-substituted ammonium cation selected from the group of[H₃NR⁸]⁺, [H₂NR⁸R⁹]⁺ and [HNR⁸R⁹R¹⁰]⁺,

-   -   Y is O, S, NH or NR⁶, or, in the case that X is NH₂ or NHR⁴, is        a chemical bond to X with formation of an imide structure,

where R² to R¹⁰ are each independently hydrocarbyl radicals having from1 to 30 carbon atoms,

with the proviso that at least one of the R², R³, R⁴, R⁵, R⁶ and R⁷radicals has at least 4 carbon atoms,

in an amount of from 1.05 to 15% by weight, based on the total amount ofthe additive concentrate, and

-   (A) at least one cold flow improver,-   (B) at least one detergent additive and-   (C) an inert organic solvent or a mixture of such solvents.

The additive concentrates mentioned preferably additionally comprise

-   (D) at least one cetane number improver.

In a preferred embodiment, the inventive additive concentrates comprise

-   -   (A) from 1 to 50% by weight, especially from 2 to 40% by weight,        in particular from 3 to 20% by weight, of at least one cold flow        improver,    -   (B) from 0.5 to 40% by weight, preferably from 0.7 to 20% by        weight, especially from 1 to 12% by weight, in particular from        1.5 to 7% by weight, of at least one detergent additive,    -   (C) from 1 to 60% by weight, especially from 3 to 50% by weight,        in particular from 5 to 40% by weight, of an inert organic        solvent or of a mixture of such solvents and    -   (D) from 0 to 80% by weight, especially from 25 to 75% by        weight, in particular from 40 to 70% by weight, of at least one        cetane number improver.

The additive concentrates mentioned may additionally comprise furtheringredients, in which case the sum of all ingredients adds up to 100% byweight.

The solubilizers of the general formula I used in accordance with theinvention ensure sufficient homogenization of additive concentrateswhich comprise both cold flow improvers and detergent additives, andalso inert organic solvents and if appropriate cetane number improvers,by stabilizing them such that no flaky precipitates or opacity occur inthe course of formulation or storage - even in the course of storageover prolonged periods, for example over several weeks - of the additiveconcentrates. The examples which follow are intended to illustrate thiseffect of the solubilizers 1.

APPLICATION EXAMPLES

Additive concentrates composed of the following components were preparedby mixing:

Solubilizer L1: Monoamide formed from maleic acid and tridecylamine(isomer mixture with <50 mol % of n-tridecylamine)[HOOC—CH═CH—CO—NH—C₁₃H₂₇] Solubilizer L2: Monoamide formed from succinicacid and tridecylamine (isomer mixture with <50 mol % ofn-tridecylamine) [HOOC—CH₂—CH₂—CO—NH—C₁₃H₂₇] Solubilizer L3: Monoamideformed from n-decylsuccinic acid and tridecylamine (isomer mixture with<50 mol % of n-tridecylamine) [HOOC—CH(C₁₀H₂₁)—CH₂—CO—NH—C₁₃H₂₇] Coldflow improver A1: Commercial reaction product formed from 1 mol ofethylenediaminetetraacetic acid and 4 mol of hydrogenated ditallow fatamine [cold flow improver of group (Ad), especially effective as aparaffin dispersant (“WASA”)] Cold flow improver A2: Commercialethylene-vinyl acetate-acrylate copolymer [cold flow improver of group(Aa)] Detergent additive B1: Commercial polyisobutylenesuccinamide basedon an aliphatic polyamine [detergent component with the (Bh) moiety]Solvent C1: Solvent Naphtha (Solvesso ® 150) Cetane number improver D1:2-Ethylhexyl nitrate Deicing agent E1: Ethylene glycol monomethyl etherBooster F1: Customary oleic acid-diethylenetriamine reaction product

The degree of homogenization of the additive concentrates prepared wasassessed visually by the following rating scale:

-   Rating 1=no precipitate, clear solution-   Rating 2=no precipitate, slight turbidity, translucent-   Rating 3=no precipitate, high opacity-   Rating 4=flaky precipitates, dispersed-   Rating 5=flaky precipitates, settled-   Rating 6=severe precipitates, sedimented, or solution gelated

The compositions of the additive concentrate prepared and the assessmentof their degree of homogenization according to the above rating scale isevident from the table below (the composition of the additiveconcentrates is reported in each case in % by weight). In all cases, L1or at least the majority of L1 was added as the last component. Thestate of the additive concentrates thus prepared which was ratedremained stable in each case for a prolonged period.

TABLE Rating of the degree of homogenization of additive concentratesExample L1 L2 L3 A1 A2 B1 C1 D1 E1 F1 Rating 1 (for 1.0 0 0 4.3 0 3.0 6030.9 0 0.8 6   compar-   ison) 2 (inventive) 3.0 0 0 4.3 0 3.0 60 28.9 00.8 1 3 (for 1.0 0 0 4.3 0 3.0 60 20.9 10 0.8  5**   compar-   ison) 4(inventive) 6.0 0 0 4.3 0 3.0 60 15.9 10 0.8  1* 5 (for 1.0 0 0 4.3 7.23.0 60 13.7 10 0.8 4-5   compar-   ison) 6 (inventive) 4.0 0 0 4.3 7.23.0 60 10.7 10 0.8 3 7 (inventive) 1.0 3.0 0 4.3 0 3.0 60 17.9 10 0.8 1* 8 (inventive) 1.0 0 3.0 4.3 0 3.0 60 17.9 10 0.8  1* *Ratingimmediately after mixing and constant after storage at 25° C. for 4weeks **Rating immediately after mixing: 2, after 1 h: 4, after 3 days:4, after 4 weeks: 5

1. The use of at least one solubilizer of the general formula I

in which R¹ denotes a hydrocarbylene radical having from 1 to 12 carbonatoms or a hydrocarbylene radical which has from 2 to 12 carbon atoms,is interrupted by one or more heteroatoms selected from the group of O,S and N, and may in each case bear one or more functional groupsselected from the group of OH, OR³, NH₂, NHR⁴, NR⁴R⁵, COOH, COOR⁷,CONHR⁴ and CONR⁴R⁵, where amino groups may also be present in protonatedform and carboxylic acid groups also in deprotonated form, X is OH, OR³,NH₂, NHR⁴ or NR⁴R⁵, where, in the case that X together with the adjacentcarbonyl group is a carboxylic acid radical, this radical is present indeprotonated form and the accompanying cation may be ahydrocarbyl-substituted ammonium cation selected from the group of[H₃NR⁸]⁺, [H₂NR⁸R⁹]⁺ and [HNR⁸R⁹R¹⁰]⁺, Y is O, S, NH or NR⁶, or, in thecase that X is NH₂ or NHR⁴, is a chemical bond to X with formation of animide structure, where R² to R¹⁰ are each independently hydrocarbylradicals having from 1 to 30 carbon atoms, with the proviso that atleast one of the R², R³, R⁴, R⁵, R⁶ and R⁷ radicals has at least 4carbon atoms, for homogenizing additive concentrates suitable foradditizing fuel oil compositions which consist predominantly of a middledistillate fuel which boils in the range of 120-500° C. and/or arenewable fuel, said additive concentrates comprising (A) at least onecold flow improver, (B) at least one detergent additive and (C) an inertorganic solvent or a mixture of such solvents.
 2. The use of at leastone solubilizer I according to claim 1 for homogenizing additiveconcentrates which additionally comprise (D) at least one cetane numberimprover.
 3. The use of at least one solubilizer I according to claim 1or 2 for homogenizing additive concentrates which comprise (A) from 1 to50% by weight of at least one cold flow improver, (B) from 0.5 to 40% byweight of at least one detergent additive, (C) from 0 to 80% by weightof at least one cetane number improver, and (D) from 1 to 60% by weightof an inert organic solvent or of a mixture of such solvents.
 4. The useof at least one solubilizer I according to claims 1 to 3 forhomogenizing additive concentrates in an amount of from 1.05 to 15% byweight, based on the total amount of the additive concentrate.
 5. Theuse of at least one solubilizer I according to claims 1 to 4 forhomogenizing additive concentrates comprising, as a cold flow improver,one or more representatives selected from (Aa) copolymers of ethylenewith at least one further ethylenically unsaturated monomer; (Ab) combpolymers; (Ac) polyoxyalkylenes; (Ad) polar nitrogen compounds; (Ae)sulfocarboxylic acids or sulfonic acids or derivatives thereof; and/or(Af) poly(meth)acrylic esters.
 6. The use of at least one solubilizer Iaccording to claim 5 for homogenizing additive concentrates, comprising,as a cold flow improver, one or more representatives selected fromethylene-vinyl acetate copolymers; ethylene-vinyl propionate copolymers;N,N-dialkylammonium salts of 2-N′,N′-dialkylamidobenzoates; the reactionproducts of 1 mol of ethylenediaminetetraacetic acid with 4 mol of adialkylamine; the reaction products of 1 mol of nitrilotriacetic acidwith 3 mol of a dialkylamine; the reaction products of 1 mol of phthalicanhydride with 2 mol of a dialkylamine; the reaction products of 1 molof an alkenyl-spiro-bislactone with 2 mol of a dialkylamine; C₁₂- toC₁₈-alkyl fumarate-vinyl acetate or C₁₂- to C₁₈-alkyl fumarate-styrenecomb polymers; and/or C₁₄- to C₂₀-alkyl itaconate comb polymers.
 7. Theuse of at least one solubilizer I according to claims 1 to 6 forhomogenizing additive concentrates, comprising, as detergent additive(B), one or more amphiphilic substances which have at least onehydrophobic hydrocarbon radical having a number-average molecular weight(Mn) of from 85 to 20 000 and at least one polar moiety which isselected from (Ba) mono- or polyamino groups having up to 6 nitrogenatoms, at least one nitrogen atom having basic properties; (Bb) nitrogroups, if appropriate in combination with hydroxyl groups; (Bc)hydroxyl groups in combination with mono- or polyamino groups, at leastone nitrogen atom having basic properties; (Bd) carboxyl groups or theiralkali metal or alkaline earth metal salts; (Be) sulfonic acid groups ortheir alkali metal or alkaline earth metal salts; (Bf)polyoxy-C₂-C₄-alkylene moieties which are terminated by hydroxyl groups,mono- or polyamino groups, at least one nitrogen atom having basicproperties, or by carbamate groups; (Bg) carboxylic ester groups; (Bh)moieties which derive from succinic anhydride and have hydroxyl and/oramino and/or amido and/or imido groups; and/or (Bi) moieties obtained byMannich reaction of substituted phenols with aldehydes and mono- orpolyamines.
 8. The use of at least one solubilizer I according to claim7 for homogenizing additive concentrates, comprising, as detergentadditive (B), one or more derivatives which derive frompolyisobutenylsuccinic anhydride and have amino and/or amido and/orimido groups.
 9. The use of at least one solubilizer I according toclaims 1 to 8 for homogenizing additive concentrates in which the inertorganic solvents (C) are selected from hydrocarbons, alcohols,carboxylic esters or mixtures thereof.
 10. The use of at least onesolubilizer I according to claims 2 to 9 for homogenizing additiveconcentrates in which the at least one cetane number improver (D) isselected from organic nitrates.
 11. The use of at least one solubilizerI according to claims 1 to 10 for homogenizing additive concentrateswhere at least one of the R², R³, R⁴, R⁵, R⁶ or R⁷ radicals in saidsolubilizer has at least 10 carbon atoms.
 12. The use of at least onesolubilizer I according to claims 1 to 10 for homogenizing additiveconcentrates, where X in said solubilizer is OH.
 13. The use of at leastone solubilizer I according to claims 1 to 12 for homogenizing additiveconcentrates, said solubilizer deriving from maleic acid or phthalicacid.
 14. The use of at least one solubilizer I according to claims 1 to13 for homogenizing additive concentrates, said solubilizer being amonoamide of maleic acid or of phthalic acid, in which at least one ofthe R² or R⁶ radicals has at least 10 carbon atoms.
 15. An additiveconcentrate suitable for additizing fuel oil compositions which consistpredominantly of a middle distillate fuel which boils in the range of120-500° C. and/or a renewable fuel, said additive concentratecomprising at least one solubilizer of the general formula I

in which R¹ denotes a hydrocarbylene radical having from 1 to 12 carbonatoms or a hydrocarbylene radical which has from 2 to 12 carbon atoms,is interrupted by one or more heteroatoms selected from the group of O,S and N, and may in each case bear one or more functional groupsselected from the group of OH, OR³, NH₂, NHR⁴, NR⁴R⁵, COOH, COOR⁷,CONHR⁴ and CONR⁴R⁵, where amino groups may also be present in protonatedform and carboxylic acid groups also in deprotonated form, X is OH, OR³,NH₂, NHR⁴ or NR⁴R⁵, where, in the case that X together with the adjacentcarbonyl group is a carboxylic acid radical, this radical is present indeprotonated form and the accompanying cation may be ahydrocarbyl-substituted ammonium cation selected from the group of[H₃NR⁸]⁺, [H₂NR⁸R⁹]⁺ and [HNR⁸R⁹R¹⁰]⁺, Y is O, S, NH or NR⁶, or, in thecase that X is NH₂ or NHR⁴, is a chemical bond to X with formation of animide structure, where R² to R¹⁰ are each independently hydrocarbylradicals having from 1 to 30 carbon atoms, with the proviso that atleast one of the R², R³, R⁴, R⁵, R⁶ and R⁷ radicals has at least 4carbon atoms, in an amount of from 1.05 to 15% by weight, based on thetotal amount of the additive concentrate, and (A) at least one cold flowimprover, (B) at least one detergent additive and (C) an inert organicsolvent or a mixture of such solvents.